The long retracting type soot blowers to which the present invention relates are of the type in which a lance tube is telescopically mounted on a feed tube and moves longitudinally between a projected position and a retracted position and rotates about its axis during such movement. In some existing types of soot blowers the lance tube is carried in a carriage and a motor is mounted for movement with the carriage and a flexible power supply is required to accommodate the movement of the motor or motors. In such previously known soot blowers the motor drives through a system of shafts and gears.
The present invention provides a drive system for a long retracting type soot blower in which the carriage carries a driven shaft by means of which the carriage is moved to move the lance tube between projected and retracted positions and by which the lance tube is rotated. A drive shaft is mounted on the soot blower frame adjacent the rear bulkhead thereof and is driven by a reversible motor fixedly mounted on the frame. The driving of the driven shaft from the drive shaft is effected by a double drum and cable assembly including drum portions mounted on the drive and driven shafts for rotation therewith, an idler pulley mounted on the frame, a lance tube-projecting cable arranged to rotate the driven shaft in a direction to move the carriage to project the lance tube in response to operation of the motor to turn the drive shaft in one direction, and a lance tube retracting cable arranged to rotate the driven shaft in a direction to move the carriage to retract the lance tube in response to reverse operation of the motor to turn the drive shaft in the opposite direction.
Although existing types of soot blowers wherein the motor travels with the carriage have important advantages under service conditions which are frequently encountered, there are other service conditions wherein the use of a flexible conductor for the power supply to the motor is undesirable because of possible hazards which arise in event a flexible electric cable is damaged or abraided. An important object of the present invention is to provide an improved drive system which eliminates the need for a flexible power supply, and which incorporates a number of other advantages in addition to compactness, low cost and reliability.
Another object is to provide such an improved soot blower driving system incorporating separate driving means for moving the lance tube forwardly and rearwardly. Thus in event the forward drive system is rendered inoperative due to mechanical failure, such as might occur due to distortion within the boiler if the lance tube should strike a boiler tube, the retracting drive system remains operative to withdraw the lance tube from the boiler.
Another object is to provide such a driving system which is readily adaptable to the provision of different driving speeds for forward and retraction travel, without the necessity of using a two-speed motor or speed control system.
Another object is to provide such a system wherein the length of the cable is not critical, and wherein any changes in length of the cable due to stretching or temperature changes do not affect the operation of the system or result in an undesirable hesitation or dwell at the reversing position. Where a single cable or chain is used, any looseness which develops introduces an aberration in the performance of the system. Such disadvantages are eliminated by the present invention.
Other objects and advantages will be apparent to those skilled in the art upon consideration of the present disclosure in its entirety.